In the production of compacted yarn, the compaction can be effected by the application of suction, e.g. to a row of orifices which can be juxtaposed with the fiber ribbon. In these systems, spun fibers and in rare cases accumulations of the spun fibers can be drawn off the yarn by suction and the suction duct, passages for other parts of the suction body can be completely or partially blocked. The suction can partly or completely fail at the perforation at which the fibers of the strands are drawn together for compaction so that yarn quality can be detrimentally affected.
Mention may be made, apart from these publications, of German patent 882 066 which discloses a drafting frame and which uses a monitoring of the feeding of short fibers between the roll pairs of a drafting frame. In this system there is no teaching of compaction. EP 0 268 217 describes a method of producing a sieve body for a friction spinning device as well as a friction spinning process. This document discloses hole cross sections which are sufficiently small to prevent penetration of fibers and which are intended to counteract the danger of stopping up. The reference does not deal with compaction systems in the sense of the invention. DE 33 42 481 describes an open-end friction spinning process and DE 36 01 358 A1 deals with an improvement thereon in the friction-spinning field.